[Bug 1835771] [NEW] MP4 fails with string argument for freeform text ('----') tags

[Simon Lambourn]

Public bug reported:

mutagen.mp4.MP4 container does not accept a string value for freeform
text tags, but expects (and returns) a bytes argument.  This is
inconsistent with python3 default of string values.

code:
>>> import mutagen.mp4.MP4 as MP4
>>> m = MP4()
>>> m['----:test:item'] = 'test value'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/mutagen/_file.py", line 75, in __setitem__
    self.tags[key] = value
  File "/usr/lib/python3/dist-packages/mutagen/mp4/__init__.py", line 375, in __setitem__
    self._render(key, value)
  File "/usr/lib/python3/dist-packages/mutagen/mp4/__init__.py", line 391, in _render
    return render_func(self, key, value, *render_args)
  File "/usr/lib/python3/dist-packages/mutagen/mp4/__init__.py", line 632, in __render_freeform
    data += v
TypeError: can't concat str to bytes
>>> m['----:test:item'] = b'test value'
>>> m['----:test:item']
b'test value'
>>> 

Expected behaviour:  accept (and return) string values, with encoding to
utf-8 if required (this is implied in some of the comments in the code).

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: python3-mutagen 1.40.0-2
ProcVersionSignature: Ubuntu 5.0.0-20.21-generic 5.0.8
Uname: Linux 5.0.0-20-generic x86_64
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Jul  8 15:03:10 2019
Dependencies:
 
PackageArchitecture: all
SourcePackage: mutagen
UpgradeStatus: Upgraded to disco on 2019-04-25 (74 days ago)

** Affects: mutagen (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug disco

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https://bugs.launchpad.net/bugs/1835771

Title:
  MP4 fails with string argument for freeform text ('----') tags

Status in mutagen package in Ubuntu:
  New

Bug description:
  mutagen.mp4.MP4 container does not accept a string value for freeform
  text tags, but expects (and returns) a bytes argument.  This is
  inconsistent with python3 default of string values.

  code:
  >>> import mutagen.mp4.MP4 as MP4
  >>> m = MP4()
  >>> m['----:test:item'] = 'test value'
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "/usr/lib/python3/dist-packages/mutagen/_file.py", line 75, in __setitem__
      self.tags[key] = value
    File "/usr/lib/python3/dist-packages/mutagen/mp4/__init__.py", line 375, in __setitem__
      self._render(key, value)
    File "/usr/lib/python3/dist-packages/mutagen/mp4/__init__.py", line 391, in _render
      return render_func(self, key, value, *render_args)
    File "/usr/lib/python3/dist-packages/mutagen/mp4/__init__.py", line 632, in __render_freeform
      data += v
  TypeError: can't concat str to bytes
  >>> m['----:test:item'] = b'test value'
  >>> m['----:test:item']
  b'test value'
  >>> 

  Expected behaviour:  accept (and return) string values, with encoding
  to utf-8 if required (this is implied in some of the comments in the
  code).

  ProblemType: Bug
  DistroRelease: Ubuntu 19.04
  Package: python3-mutagen 1.40.0-2
  ProcVersionSignature: Ubuntu 5.0.0-20.21-generic 5.0.8
  Uname: Linux 5.0.0-20-generic x86_64
  ApportVersion: 2.20.10-0ubuntu27
  Architecture: amd64
  CurrentDesktop: ubuntu:GNOME
  Date: Mon Jul  8 15:03:10 2019
  Dependencies:
   
  PackageArchitecture: all
  SourcePackage: mutagen
  UpgradeStatus: Upgraded to disco on 2019-04-25 (74 days ago)

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